This invention relates to providing a microchannel chip device which will be able to perform a large number of bio molecule tests simultaneously, as well as producing a uniform test environment for each biomolecule test and eliminate the statistical test to test variations.
It is known in fluid dynamics that, due to the viscosity of the biological sample containing fluid, which is usual water, the dynamic pressure to pass this fluid through and into the multiple channel glass panel increases as the microchannel diameter is reduced and the glass plate thickness increases. Threshold values are such that, below 10 micrometers in channel diameter, increase in vacuum pressure is required to force water through the microchannels, and also structural integrity of the glass sample then becomes problematic. However, on the other side, by increasing channel diameter beyond 10 microns and reducing the thickness of the glass plate, vacuum pressure is still required but to a lesser extent, while undesirable artifacts are generated in particular increased diffuse halos around the top access mouth of the channels. These undesirable artifact halos considerably deteriorate both the image quality and the sensitivity of the test.
It is noted that fluid dynamics in a microchannel are not the same as those in diametrally larger tubes, e.g. a water filled coffee mug. Indeed, because of the larger inner diameter of a coffee mug, when a water filled coffee mug is tilted from an upright condition to a laterally inclined position, the top surface menisk of the volume of water will not concurrently tilt and thus will remain parallel to the ground in both instances, although the longitudinal axis of the mug is no longer vertical in its tilted condition. On the other end, due to surface tension properties and viscosity of the water and due to the micrometer grade diameter of the microscopic (micro-) channel, when a microchannel is tilted from an upright condition to a laterally inclined condition, the menisk will not stay parallel to the ground as it did in larger diameter cylinder such as a coffee mug, and it will tilt. With the tilted microchannel so that the perpendicular axis to the top surface menisk of the water volume inside the tilted microchannel will remain coaxial to the longitudinal axis of the tilted microchannel.
U.S. Pat. No. 5,843,767 issued on Dec. 1st 1998 to HOUSTON ADVANCED RESEARCH CENTER (inventor: Kenneth BEATTIE)xe2x80x94hereinafter the xe2x80x9cBeattie patentxe2x80x9d, discloses a device for binding a target molecule, comprising a substrate having a multiplicity of discrete tubes extending transversely therethrough. These tubes extend orthogonally to the top surface of the substrate. A first binding reagent is immobilized on the walls of a first group of tubes, while a second binding reagent is immobilized on the walls of a second group of the tubes. Such device is for use in the identification or characterization of nucleic acid sequences through nucleic acid probe hybridization with samples containing an uncharacterized polynucleic acid, e.g. recombinant DNA, polymerase chain reaction fragments, etc . . . as well as other biomolecules.
In the Beattie patent, these tubes are claims limited to a diameter ranging between about 0.03 to 10 micrometers. The reason for the top threshold diameter value is that if your have upright tubes or channels as in Beattie, any diameter larger than about 10 micrometers will enlarge optical halo artifacts at the top access mouth of the tubes, and accordingly, much reduced sensitivity.
During the 1990s, microfabrication technology has enables miniaturization and automation of manufacturing processes in numerous industries. The impact of microfabrication technology in biomedical research can be seen in the growing presence of microprocessor controlled analytical instrumentation and robotics in the laboratory engaged in high throughput genome mapping and sequencing (see the current xe2x80x9cHuman Genome Projectxe2x80x9d, with its first phase just completed). Optical detection of fluorescent labelled receptors is employed inter alia in detection for sequencing. Detection can be achieved through use of a charge coupled device array, or confocal laser imaging technology such as DNA scope (TM).
Capillary tube glass arrays are already in use as high surface area nanoporous support structures to tether DNA targets or probes for hybridization. Such capillary tube glass wafers contain a regular geometric array of parallel holes or tubes as small as 33 nanometers in diameter, or as large as several micrometers in diameter. These holes or tubes serve as sample wells for placement of a substantially homogeneous sample of a biomolecule within each hybridization site. The orifices are fabricated using excimer laser machining.
However, such prior art microscopic detection devices usually require charged coupling devices, and cannot scan the full sample area. This is because, as in the Beattie patent, since you have vertical micro-channels, the diameter thereof larger than 10 micrometers will produce much larger optical halo artifacts and will bring about much diminished microscopic sensitivity. This is why the claimed microchannel diameter in the Beattie patent is limited to a range from 0.03 to 10 micrometers.
Methods are also known in the art for delivering sub-nanoliter microdroplets of fluids to a surface at submicron precision. A microjet system or a microspotter, capable of delivering subnanoliter DNA solution to the wafer surface, can thus be employed.
An important object of the present invention is therefore to improve upon the above-noted prior art technology, in particular to that disclosed in the Beattie patent, supra, by providing a device which will be able to perform a large number of bio molecule tests simultaneously, as well as producing a uniform test environment for each biomolecule test and eliminate the statistical test to test variations.
A further important object of the present invention is to use the capillary tube as an environment that can produce an internal reflection known as xe2x80x9cpipping effectxe2x80x9d, so as to increase sensitivity and resolution of biomolecule detection.
Still another object of the invention is to use the capillary tube as an environment in which samples and reagents flow through, to increase the interactions between biomolecules so as to reduce the incubation time and increase the sensitivity and resolution at the same time, to thus enable use of a more diluted sample for the same efficiency.
A general object of the invention is to reduce labour costs and required effective sample volume associated with operation of such devices.
According to the invention, there is disclosed a rigid panel chip for supporting biological samples for observation with a microscope, said glass panel defining a top flat surface, a bottom bearing surface, and at least a few channels extending generally parallel to each other from said top to bottom surfaces, each of said channels defining a top access mouth for ingress of said biological samples, wherein each of said channel is obliquely inclined so as to make an acute angle relative to an axis perpendicular to said top flat surface, and each said channel having such an inner diameter as to accommodate flow through viscosity of a biological sample containing fluid.
Preferably, the panel chip consists of either glass, quartz, polypropylene, polyolefin, nylon, or fused silica. More preferably, the panel chip will be made from transparent glass. Most preferably, the glass chip will have a thickness ranging between 0.5 to 5 millimeters.
Preferably, said channels are cylindroid. Preferably, said cylindroid channels have a constant diameter ranging between 10 to 500 micrometers, more preferably, between 50 to 200 micrometers, and most preferably, of about 100 micrometers.
Said acute angle should range between 20 to 80 degrees, and preferably be about 42 degrees.
Preferably, the number of said channels range between a few hundreds to a few thousands of said channels extending through the thickness of said glass panel.
The invention also relates to a method of observation by flat surface laser scanner of biological samples in a glass panel, the glass panel of the type defining a top flat surface, a bottom bearing surface, and a plurality of channels extending generally parallel to each other from said top to bottom surfaces and each defining a top access mouth for the biological sample, the method including the following steps:
a) inclining the channels in an oblique fashion so as to make an acute angle relative to an axis perpendicular to the top flat surface of the glass panel,
b) enlarging the inner diameter of each said channel enough as to accommodate reduced vacuum assisted flow through viscosity of a biological sample containing fluid;
c) providing fluorescein dyes inside the biological sample containing fluid;
d) directing a coherent laser beam transversely through a selected channel top access mouth and coaxially into the corresponding channel, so as to excite the fluorescein dyes, wherein an optically apparent glow is generated by the excited fluorescein dyes without a halo being generated about the top access mouth;
e) allowing sufficient time for the fluorescein dyes to project the optically apparent glow upwardly beyond said channel top access mouth; and
f) performing optical measurements of this upward out of channel projecting fluorescein glow by flat surface laser scanner to generate evidence data on the chemical properties of the biological samples.